Electric handheld devices, for example mobile radio units, computer mice, remote controls or the like increasingly are provided with capacitive touch sensors and proximity sensors in order to detect a contact of the handheld device by a hand or an approach of a hand towards the handheld device, respectively, and to activate a predetermined device function at a contact with or an approach towards the handheld device.
Capacitive sensors, such as those used in electric handheld devices, substantially consist of an evaluation device and of a number of electrodes or sensor electrodes, respectively, coupled with the evaluation device. In doing so, the electrodes are manufactured or assembled separately and are arranged on a rigid or flexible printed circuit board specifically provided for the electrodes. The electrodes or the printed circuit board, respectively, on which the electrodes are arranged, are connected via plug-in connections to the evaluation device, which also is arranged on a printed circuit board.
In doing so, it is a disadvantage that additional cost is incurred for the printed circuit boards, on which the electrodes are arranged, and for the plug-in connections. In very cost-sensitive applications these additional cost may lead to abstain from the use of a capacitive sensor. In addition, the above described design of a capacitive sensor device leads to the fact that also the effort and the cost of manufacturing of an electric handheld device are increasing, because additional working steps are required for manufacturing in order to, on the one hand, produce the printed circuit boards comprising the electrodes arranged thereon and, on the other hand, to couple the electrodes or the printed circuit board, respectively, with the evaluation device.
In order to reduce the time and effort and the cost for manufacturing capacitive sensor devices, in particular for handheld devices, it is known to simplify the design and the manufacturing process of the printed circuit boards comprising the electrodes arranged thereon. For example, whenever possible only one-sided printed circuit boards without a ground surface on the backside are used. Furthermore, it is feasible to produce the electrodes by means of applying electrically conductive color onto a cost-effective carrier material. In a further alternative embodiment, for example, the electrodes may be realized as pierced sheet metal parts.
Furthermore, it is known to reduce the time and effort and the cost for manufacturing the capacitive sensor device by providing cost-effective alternatives instead of the above mentioned plug-in connections, for example springs or electrically conductive elastomers as connecting elements in order to connect the electrodes or the printed circuit board, on which the electrodes are arranged, with the evaluation device.
This way, the material cost of a capacitive sensor device may be reduced, however, the time and effort and the cost, respectively, for manufacturing the capacitive sensor device substantially remain the same, so that by means of the measures mentioned the effort for manufacturing an electric handheld device comprising at least one capacitive sensor cannot be reduced substantially.